Isolation of a distally located gene possibly correlated with gametocyte production ability

Abstract

Previous studies were focussed on the attempt to correlate observable variations in the size of Plasmodium berghei chromosomes with the loss of ability to produce viable gametocytes. A temporal coincidence between the appearance of a subtelomeric deletion on P. berghei chromosome 5 and the loss of the ability to produce viable gametocytes was observed in a clone (HPE) directly derived from the high gametocyte-producer clone 8417 during mechanical passages. Interestingly enough, three P. berghei sexual-specific genes have already been mapped on internal fragments of this chromosome. A novel gene, clone 150, isolated from a genomic library of clone 8417 using a probe enriched for sexual-specific transcripts, maps on chromosome 5 within 100kb from the telomere. Subtelomeric deletions of chromosome 5 affecting two non-producer clones involve part of the transcribed region of this gene.

Heterogeneous ribosome populations are present in Plasmodium berghei during development in its vector

“…The expression of different ribosome forms may therefore have arisen in response to a requirement for optimization of the translation of this specific set of genes. It is notable, furthermore, that the S‐type C rRNA gene of P. berghei is one of a number of sexual stage‐specific genes located on chromosome 5 (Rawlings et al ., 1992; Paton et al ., 1993; Birago et al ., 1994; Waters et al ., 1997). As the transcriptional activity of genes can be modulated by their chromosomal position or regulated in concert with other genes within a linkage group (Wilkinson et al ., 1989), it is possible that the transcription of S‐type rRNA genes and other sexual stage‐specific plasmodial genes are regulated by common mechanisms.…”